Clinical Utility of Tumor Markers

Tumor markers comprise a wide spectrum of biomacromolecules excessively synthesized by a variety of neoplastic cells. These markers can be endogenous products of highly active metabolites from malignant neoplastic cells or the products of newly activated genes. Ideally, tumor markers should be highly sensitive, specific, and reliable with a high prognostic value and organ specificity. In addition, they should reflect the tumor stage. However, no tumor markers identified thus far have all of these characteristics. Nevertheless, most tumor markers show excellent clinical relevance for monitoring the efficacy of a variety of therapies. We herein review how to use the recommended tumor markers to diagnose malignancies, such as gastrointestinal carcinoma, liver cancer, bile duct/pancreatic cancer, lung cancer, breast cancer, gynecologic cancer, and urologic cancer.